A heavy duty (well, robust) articulated joint
This joint is designed to be made from 6mm mdf laminated together with M8 bolts and spacers as the pivots.
There are only three manufactured parts in the joint (leaf 1, leaf 2 and a spacer). To get the different configurations, just change the order of the lamination. Some of the pieces have a 3mm deep by 6mm wide slot to allow a bolt (M6) to be inserted (so that it could be mounted)
The joint between the two centre sub assemblies isn't very strong- its just a butt joint. Some interim bolted plate is probably required, but hey, its a thing in progress.
I've allowed bolt holes for adding M4 screws to hold the laminated blocks together (just in case you don't want to rely on glue).